Anti-adhesion Performance Research Articles

Transparent PDMS Surfaces with Covalently Attached Lubricants for Enhanced Anti-adhesion Performance.

Liquid-like surfaces featuring slippery, omniphobic, covalently attached liquids (SOCALs) reduce unwanted adhesion by providing a molecularly smooth and slippery surface arising from the high mobility of the liquid chains. Such SOCALs are commonly prepared on hard substrates, such as glass, wafers, or metal oxides, despite the importance of nonpolar elastomeric substrates, such as polydimethylsiloxane (PDMS) in anti-fouling or nonstick applications. Compared to polar elastomers, hydrophobic PDMS elastomer activation and covalent functionalization are significantly more challenging, as PDMS tends to display fast hydrophobic recovery upon activation as well as superficial cracking. Through the extraction of excess PDMS oligomers and fine-tuning of plasma activation parameters, homogeneously functionalized PDMS with fluorinated polysiloxane brushes could be obtained while at the same time reducing crack formation. Polymer brush mobility was increased through the addition of a smaller molecular silane linker to exhibit enhanced dewetting properties and reduced substrate swelling compared to functionalizations featuring hydrocarbon functionalities. Linear polymer brushes were verified by thermogravimetric analysis. The optical properties of PDMS remained unaffected by the activation in high-frequency plasma but were impacted by low-frequency plasma. Drastic decreases in solid adhesion of not just complex contaminants but even ice could be shown in horizontal push tests, demonstrating the potential of SOCAL-functionalized PDMS surfaces for improved nonstick applications.

Biosafe Polydopamine-Decorated MnO2 Nanoparticles with Hemostasis and Antioxidative Properties for Postoperative Adhesion Prevention.

Surgical bleeding and cumulative oxidative stress are significant factors in the development of postoperative adhesions, which are always associated with adverse patient outcomes. However, effective strategies for adhesion prevention are currently lacking in clinical practice. In this study, we propose a solution using polydopamine-decorated manganese dioxide nanoparticles (MnO2@PDA) with rapid hemostasis and remarkable antioxidant properties to prevent postsurgical adhesion. The PDA modification provides MnO2@PDA with enhanced tissue adhesiveness and hemocompatibility with negligible hemolysis. Furthermore, MnO2@PDA exhibits impressive antioxidant and free radical scavenging properties, protecting cells from the negative effects of oxidative stress. The hemostatic activity of MnO2@PDA is evaluated in a mouse truncated tail model and a liver injury model, with results demonstrating reduced bleeding time and volume. The in vivo test on a mouse cecal abrasion model shows that MnO2@PDA exhibits excellent antiadhesion properties coupled with alleviated inflammation around the damaged tissue. Therefore, MnO2@PDA, which exhibits high biosafety, rapid hemostasis, and beneficial antioxidant capacity, displays exceptional antiadhesion performance, holding great potential for clinical applications to prevent postoperative adhesion.

Improving the Physical Properties of Starch-Based Powders for Potential Anti-Adhesion Applications.

Postoperative adhesion is one of the most common complications that occur during and after surgery; thus, materials that can prevent adhesion are often applied. Starch powders with a high water absorption capacity are preferred, and many studies have focused on increasing the water absorption of modified starches, as native starch powders display poor water-holding capacities. The effects of salts on the physical properties of acetylated distarch phosphate potato starch powders were investigated here. Changes in functional groups, the crystal structures of modified starch, particle morphologies, water absorption, viscosity, and in vivo adhesion were investigated. The results showed that salts greatly improved the water absorption and viscosity of acetylated distarch phosphate potato starch powders. Among the three different salt-modified starch powders, NaCl-modified starch powders displayed higher water absorption and viscosity and demonstrated better in vivo anti-adhesion performance. The results of this study propose a potential biomaterial that may function as an anti-adhesive, potentially leading to reduced surgical risks and a better quality of life for patients.

PLLA-COI multilayer nanofiber membrane for anti-adhesion of the Achilles tendon

Peritendinous Adhesion is a complication after surgery for Achilles tendon injury. This complication can be treated with surgical stents. Anti-adhesion membrane is an effective scaffold material to prevent adhesion. However, currently available PLA anti-adhesion membranes have the problems of poor anti-adhesion performance and low healing effect on the Achilles tendon. In this study, combined the advantages of L-polylactic acid (PLLA) hydrophobicity and Collagen type I (COI) hydrophilicity, a PLLA-COI multilayer nanofiber membrane composed of a multilayer structure was prepared by solution electrospinning and characterized its morphology, physical, mechanical, and in vitro properties. The membrane has a structure characteristic of gradually decreasing fiber diameter, increasing porosity and increasing hydrophilicity from the outer to the inner layer. The cell experiment results show that the PLLA-COI multilayer nanofiber membrane has good cell compatibility. We also carried out in vivo research with the rabbit Achilles tendon adhesion model. The results indicate that the membrane has an excellent anti-adhesion effect and strong hydrophilicity, effectively promoting Achilles tendon injury recovery and preventing adhesion. In addition, this membrane does not require sutures for surgery, effectively reducing the complexity of use, with great potential in preventing peritendinous adhesion.

Waterproof organic-inorganic composite with fast reversible photochromic switch for UV indication and information storage

Design and preparation of photochromic materials with reversible color change under specific wavelength irradiation have been active research fields. However, these existing materials face a great challenge in rapid responsiveness and effective water management. Here, a waterproof composite with fast light response was successfully prepared by air-jet electrospinning and subsequent spray treatment. Specifically, its response time and saturation time are reduced to a few seconds and 1 min, respectively. Its reflectivity at 670 nm changes from 77.50% to 6.26%, which strongly indicates the large color contrast of this composite. Its natural fading process only takes 1 h, and infrared radiation can further reduce the erasure process to a few seconds. Concurrently, this material possesses hydrophobic properties and anti-adhesion performance, providing superior protection for its photochromism. Overall, this waterproof composite possesses rapid photochromism and appropriate spontaneous fading efficiency, enabling it to have a very broad application prospect in the fields of indicator materials, anti-counterfeiting materials, personalized labels, etc.

P11 Lubricant-infused silver-polytetrafluoroethylene coated urinary catheters inhibit adhesion of host-secreted proteins and biofilm formation

Abstract Objectives The adhesion of specific host-derived proteins (particularly fibrinogen) and subsequent biofilm formation play a central role in the pathogenesis of catheter-associated urinary catheter infections (CAUTIs). However, very few catheter materials have proven to be able to simultaneously prevent both bacterial and protein adhesion in a complex physiological environment (i.e. urine). The aims and objectives of this research were to (i) develop silver-polytetrafluoroethylene (AgF)-based coatings with a wide range of surface energies; (ii) test their antifouling performance; and (iii) investigate the influence of surface energy on biofouling accumulation. Methods Standard AgF coatings with tailored surface energies (ranging from 18 mJ/m2 to 42 mJ/m2) were fabricated using an electroless method. By spontaneous polycondensation 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) onto the AgF sublayer, a lubricant-infused AgF coating (AgFP) was obtained. The surface morphology, chemical composition, and roughness were characterized by SEM, EDS and AFM, respectively. The surface energy was characterized using a contact angle approach and calculated using the Van Oss method. The anti-adhesion performance of the coated catheters against proteins (fibrinogen [Fgn]; BSA) and bacteria (Escherichia coli; Proteus mirabilis) was examined and compared with commercial all-silicone catheters. Results The results showed that there exist two separate optimum surface energies where bacterial (∼25 mJ/m2) and protein adhesion (∼35 mJ/m2) are minimal (Figure 1). The deposition of fibrinogen on surfaces significantly accelerated bacterial attachment and biofilm formation, whereas the AgFP coating with the smoothest surface and ultralow surface energy (∼12 mJ/m2) displayed significant antibiofilm and anti-protein activities compared with uncoated silicone surface traditional AgF coatings (Figure 2). Figure 1.Surface energy on adhesion of bacteria and proteins. Figure 2.Biofilm formation on Si, AgF and AgFP surfaces after 1 day co-culture in pure bacterial suspension and protein-supplemented bacterial suspension. Scale bars correspond to 40 μm. Conclusions The inclusion of lubricant into the AgF matrix leads to the formation of a smooth and super-repelling catheter surface, leading to ultralow adhesion for both bacteria and proteins. Surprisingly, our results indicated that there exists an optimum surface energy where the adhesion of both bacteria and proteins is minimal, which further extended the classic ‘Baier curve’.

Antiadhesion Superhydrophobic Bipolar Electrocoagulation Tweezers with High Conductivity and Stability.

Irregularly shaped electrosurgical devices face significant challenges in electrosurgery due to serious blood and tissue adhesion. Superhydrophobic surfaces inspired by lotus leaves have attracted great attention for their promising antiadhesion properties. However, there are few methods for efficiently preparing superhydrophobic irregularly shaped bipolar electrocoagulation tweezers (BETs). Herein, we propose a simple and environmentally friendly method to fabricate antiadhesion superhydrophobic surfaces on BETs. The superhydrophobicity is obtained by combining laser texturing to form rough structures and low surface energy modification via stearic acid. The formation mechanism of superhydrophobicity is investigated through analyzing microstructures and chemical compositions by scanning electron microscopy, white-light interferometry, and X-ray photoelectron spectroscopy. The functionalized BET surfaces exhibit excellent water repellency with a contact angle of 159.6°, a roll-off angle of 1°, and a surface energy of 14.3 mJ/m2, possessing excellent antiadhesion properties against blood, chicken breast tissue, and pork tissue. Compared with ordinary BETs, the mass of blood, pork tissue, and chicken breast tissue adhered to the superhydrophobic BET is reduced by 97.70, 70.34, and 75.35%, respectively. Moreover, the superhydrophobic BETs have excellent conductivity and maintain good antiadhesion properties after low-temperature storage for 2 weeks, after being impacted by sand and blood and 30 cycles of tape peeling tests. With outstanding antiadhesion performance, the superhydrophobic BET may have promising application prospects in the electrosurgery field.

Dynamic behavior of biological droplets on heated, superhydrophobic microstructured surfaces

Severe adhesion of biological fluids occurs on surgical electrodes due to a temperature-induced physical mechanism. By constructing surface microstructures and improving their hydrophobicity, it becomes a favorable choice for electrode anti-adhesion, but the related mechanisms are still not fully understood. Herein, we investigated the dynamic behavior of water and biological droplets on superhydrophobic microstructured surfaces (SMSs) heated over 100 ℃. The design inspiration of SMSs is derived from purple orchid leaves with excellent self-cleaning properties. The SMSs with Cassie-Baxter and Cassie impregnating states were selected and a flat surface was employed for comparison. Results show that the SMSs with the Cassie-Baxter state could reduce the Leidenfrost point to form a pseudo-Leidenfrost effect for water droplets. Furthermore, the dynamic evolution mechanism of plasma droplets on heated surfaces was first proposed, including base shrinkage, coagulation growth, and cap convergence. For the SMSs with the Cassie-Baxter state, the heat was carried away by vapor from the cavities at the contact interface, so that the growth height of the coagulation was lower than that of other surfaces. Additionally, the mentioned SMSs exhibited outstanding anti-adhesion performance and thermal stability. This study may contribute to understanding the anti-adhesion mechanism of surgical electrodes at the microscopic level.

Di-particles-derived slippery lubricant-infused porous surface with broad anti-adhesion performance

As an alternative approach to superhydrophobic surfaces, slippery lubricant-infused porous surface (SLIPS) is a promising solution to undesirable adhesion. Nonetheless, it is highly expected yet still challenging to exploit a method featured substrate-independence, time-saving property and long-term stability. In this study, different from the common preparation process of SLIPS, the di-particles-derived slippery lubricant-infused porous surface (DPD-SLIPS) was successfully fabricated derived from strategically inverted construction of highly stable and superhydrophobic di-particles framework for locking lubricant via successively-two-step spraying polyacrylate adhesive nanoparticles (NPs) and fluorinated SiO2 NPs, followed by perfluoropolyether (PFPE) infiltration. This substrate-independent procedure is time-saving and adaptable for a variety of materials with distinct morphologies and dimensions. The resultant surface hierarchy exhibited excellent mechanical robustness and lubricant-locking ability when subjected to adhesive tape peeling, abrasion, and shearing tests. Furthermore, the anti-adhesion performance of the created surface was investigated under diverse conditions, exhibiting remarkable ultra-slipping, drag reduction, anti-biofouling, self-cleaning, and anti-icing properties. In particular, the construction of such low surface energy base with micro/nano hierarchical structure via a facile spraying method is an advanced candidate for real applications in reducing ship drag, marine antifouling, preventing biological invasion, among others.

Daphnia-inspired dynamic slippery chemically bonded liquid surface for the active prevention of covalently attached foulant adhesion.

Engineering anti-adhesion coatings always focuses on a specific hierarchy and surface free energy, which passively endures water scouring to wash away the loosely attached foulants. Certain foulants, however, especially those that are highly adhesive or covalently attached on the coatings, cannot be removed off the designed surfaces easily. Inspired by the active self-hunting behavior of the filter-feeding animal Daphnia, herein, we propose a universal antifouling strategy with both passive and active adhesion repellency capabilities. The premise for this protocol is that the as-fabricated liquid-like surface is able to repel the settlement of general foulants upon static conditions. Under steady thermal stimuli, the dynamic liquid-like surface behaves like a boxer with an active prevention ability against highly adhesive foulant adhesion, e.g., proteins, crude oils, and even covalently adhered mussel species. The enhanced biocide-free anti-adhesion performance is attributed to the reversible non-covalent interactions of pollutants in the initial contact with the surface, which was innovatively proved by AFM tapping tests to elucidate the physicochemical interactions between the foulants and coating surfaces. We envision that such an active anti-covalent adhesion surface may have great potential in diverse fields, including marine antifouling, fluid handling and transportation, and energy-harvesting devices.

Fabrication of Hierarchical Patterned Surfaces Using a Functionalized CeO2-EPDM Composite for Crevice Corrosion Prevention on High-Voltage Insulators.

Crevice corrosion accounts for 62% of the recorded breakdown of insulators utilized in transmission lines, which may interfere with the reliability of power utilities. To address these challenges, sustainable and resilient slippery lubricant-infused porous surfaces (SLIPS) are developed on insulators to prevent electrochemically/biochemically induced crevice corrosion especially occurring in tropical and coastal environments. The conventional way of developing SLIPS by chemical and physical etching might interfere with the mechanical stability of insulators composed of pin (galvanized steel), cement, and shell (porcelain). The current study proposes a noble concept of developing hierarchical patterned textured surfaces on insulators to fabricate a resilient SLIPS coating without physical/chemical etching. The proposed coating exhibits 99% antiadhesion performance against a mixed culture of bacterial strains, superior hydrophobicity (contact angle: 160°, contact angle hysteresis: 4°), and crevice corrosion resistance performance at elevated temperatures (25-75 °C) and humidity. This study could facilitate a new route for the development of sustainable and highly reliable SLIPS coatings in the future.

Evaluation of the optimal dose for maximizing the anti-adhesion performance of a self-degradable dextran-based material

LYDEX, which is a hydrogel composed of aldehyde-functionalized dextran and succinic anhydride-treated ε-poly-L-lysine, was previously developed by our group as a self-degradable adhesive with an excellent functionality. As a result, this hydrogel has been investigated for a wide range of medical applications, including hemostatic agents, sealants, wound dressings for endoscopes, and anti-adhesion materials. Previously, the unique potential of LYDEX to control the in vivo degradation rate depending on its composition was verified for use in anti-adhesion applications. Although the gel thickness also plays a significant role in determining the degradation rate, this issue was not sufficiently investigated in previous studies. Thus, in the current study, the optimal LYDEX dose (film thickness) for maximizing the anti-adhesion material performance was verified using a rabbit colon model and it was confirmed that the gel film thickness affects the degradation period and anti-adhesion effect. The obtained results suggest the potential for designing LYDEX materials suitable for application at a wider range of in vivo treatment sites, which could be extremely valuable for the development and use of novel anti-adhesion materials with adequate hemostatic and sealant performances.

Effect of volcano-like textured tools on machining of Ti-6Al-4V alloy: a numerical and experimental analysis

Higher temperature and lower thermal conductivity between the tool-chip contact face easily result in adhesion and wear on the tool surface which negatively affects the tool life and the machining quality of the workpiece in the machining Ti-6Al-4V alloy process. To address these problems, the investigation, combining the simulation and experiment, introduced the volcano-like textures of different diameters with excellent anti-adhesion performance on the tool rake face. Deform-3D software with updated Lagrangian formulation was used for numerical simulation, and the thermo-mechanical analysis was performed using the Johnson-Cook material model to predict the cutting forces, cutting temperature and tool wear. In machining experiments, volcano-like textures (VT) with different diameters were fabricated by fiber laser on the rake face of cemented carbide tools close to the main cutting edge. Experiments in machining Ti-6Al-4V alloy were carried out with the textured tools and non-textured tool under rough machining, semi-finishing and finishing conditions. Then, cutting force, cutting temperature and tool wear were investigated. The results showed that textured tools generally perform better than non-textured tool. The cutting force of VT1 was reduced by 31.2% and 50%, respectively, compared with the non-textured tool under semi-finishing and finishing conditions. With the refinement of machining, the cutting performance of the textured tools is improved, and the service life of the tool is extended. Therefore, the investigation can provide a basis for the surface texture design and optimization of the carbide tool.

Combined treatment of xyloglucan derivative hydrogel and anti-C5a receptor antibody in preventing peritoneal adhesion

Postoperative peritoneal adhesion is a common complication after surgery with high morbidity. In addition to improving surgical operations, medical therapy and physical barriers are the two main ways to prevent postoperative peritoneal adhesion. Satisfactory efficacy is not often obtained by the single antiadhesion method, and the combination of barrier therapy and antiadhesion drugs has attracted more attention. In this study, we first demonstrated that aberrant complement activation was associated with peritoneal injury and inflammatory responses. Correspondingly, blocking the C5a-C5aR axis reaction effectively reduced inflammatory reactions. Therefore, we creatively developed an integrated treatment of xyloglucan derivative (mXG) hydrogel and intravenous anti-C5a receptor antibody (anti-C5aRab) aimed at peritoneal adhesion, and then systematically evaluated the therapeutic efficacy using a sidewall defect-cecum abrasion model in mice. In vitro and in vivo experiments showed that the mXG hydrogel had good biocompatibility and degradability and could serve as a safe anti-adhesion barrier. The results showed that anti-C5aRab treatment could significantly inhibit peritoneal adhesions by reducing neutrophil infiltration and the expression of phosphorylated Smad2. Taken together, the mXG hydrogel integrated with anti-C5aRab showed superior antiadhesion performance and holds promising clinical applications in preventing peritoneal adhesion. STATEMENT OF SIGNIFICANCE: Postoperative peritoneal adhesion is an urgent problem to be solved after surgery. Previously, a biodegradable and thermoreversible xyloglucan derivative (mXG) hydrogel was developed that effectively prevented postoperative peritoneal adhesions, but obvious inflammatory responses and proliferation could still be observed. In addition, aberrant complement activation is associated with a variety of inflammatory diseases. We demonstrated that aberrant complement activation is involved in peritoneal adhesion. In this work, mXG hydrogel and intravenous anti-C5a receptor antibody (anti-C5aRab) were integrated to address peritoneal adhesions. The anti-C5aRab reduced the inflammatory responses. In addition, the mXG hydrogel was easy to use and effectively isolated the wound surface at the local injury site. Overall, this integrated treatment significantly improved the antiadhesion effect.

Adhesion behavior of different droplet on superhydrophobic surface of cotton fabric based on oxygen plasma etching

Oxygen plasma etching followed with spraying of hydrophobic suspension containing SiO2 nanoparticles were used to construct superhydrophobic cotton fabric, and the adhesion behavior of the superhydrophobic surface to deionized water, dye liquor, sterile defibrinated sheep blood, and simulated blood solutions was studied and evaluated in focus. Results of the present study showed the water contact and water slip angles of the superhydrophobic cotton fabric were 158.6° and 7.3° with 5 wt% of hexadecyltrimethoxysilane (HDTMS). The plasma etching imparted uniform strip grooves on the fiber, which together with the deposition of SiO2 nanoparticles constituted a dual-scale rough structure on the fabric surface. FTIR analysis showed the successful combination of HDTMS and SiO2 nanoparticles and covering on the cotton surface. This superhydrophobic surface possessed hydrophobic effect even after 35 times of abrasion and immersion in strong acid or alkali solutions for 8 h. The surface tension and viscosity of simulated blood and sterile defibrinated sheep blood (SDSB) were similar, with a contact angle of only 139.7° and a slip angle above 20°. And their adhesion forces were calculated by the Cassie-Baxter equation to be 30.93 and 37.88 μN. Moreover, the droplets placement of simulated blood and SDSB on the superhydrophobic surface for 2 h caused trace adhesion but no penetration. This indicated that the superhydrophobic surface had anti-adhesion performance to the liquids. In conclusion, it was evident that the superhydrophobic fabric has good application prospects in the field of textiles for daily life and medical protection.

N, O-carboxymethyl chitosan/oxidized cellulose composite sponge containing ε-poly-l-lysine as a potential wound dressing for the prevention and treatment of postoperative adhesion

Herein, we designed and fabricated a biodegradable composite sponge which main component contained N, O-carboxymethyl chitosan (N,O-CS) and oxidized cellulose nanocrystals (TOCN) as a potential wound dressing for the prevention and treatment of postoperative adhesion. In order to improve antimicrobial properties of N,O-CS/TOCN composite sponges, natural antimicrobial agents (ε-Poly-l-Lysine，EPL) were successfully introduced and the EPL/N,O-CS/TOCN composite sponge exhibited excellent antibacterial properties and biological security. The EPL/N,O-CS/TOCN composite sponge can be degraded in vivo within 3 weeks. Finally, we analyzed the anti-adhesion performance of EPL/N,O-CS/TOCN composite sponge through a rat model of sidewall defect-cecum abrasion. These results demonstrated that EPL/N,O-CS/TOCN-treated group can effectively reduce the peritoneal adhesion formation than the commercial soluble gauze group and normal saline group, which mainly attribute to the excellent hemostatic function and tissue repair function of EPL/N,O-CS/TOCN composite sponge. It is believed that the EPL/N,O-CS/TOCN composite sponge will prove to be as a new medical device treat the internal tissue/organ repair and simultaneous prevention of postoperative adhesion.

Temperature-triggered fluorocopolymer aggregate coating switching from antibacterial to antifouling and superhydrophobic hemostasis

The multifunction antibacterial hemostatic materials can reduce blood loss, infection and wound complications, which probably decrease morbidity and health care costs. However, the contradictory relationship between antibacterial ability and biocompatibility, and the unnecessary blood loss restricts the practical application of hydrophilic cationic antibacterial hemostatic materials. Herein, a multifunctional temperature-triggered antibacterial hemostatic fluorocopolymer aggregate coating was developed. After self-assembly and quaternization process, the quaternized poly(N,N-dimethylaminoethylmethacrylate)-b-poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) block copolymers (PDMA-b-PFOEMA) aggregate coating consisting of fluoropolymer and quaternary ammonium salt were built. The synergistic effect on fluorinated block with low surface energy and quaternary ammonium salt block with bactericide activity severs the way of initial bacterial attachment and proliferation, while the migration of fluorinated block greatly promotes the biocompatibility and anti-adhesion performance in response to the switch from room temperature to physiological temperature. Furthermore, the fluorocopolymer aggregate coating with hydrophobic properties possessed the property of rapid coagulation, low blood loss, minor secondary bleeding and least bacteria infiltration. The multifunctional temperature-triggered fluorocopolymer aggregate coating with antifouling, antibacterial and hemostatic properties may have a great potential in the biomedical application.

Effect of filler on adhesion characteristics of precursor ceramic coating against high-temperature molten ash

Abstract In view of the widespread high-temperature molten ash adhesion problem of heat exchanger surface in the chemical, power, metallurgy and other industries, precursor ceramic coating is proposed to reduce ash adhesion strength. Three ceramic coatings were obtained by adding hexagonal boron nitride (h-BN), zirconia (ZrO2) and aluminium oxide (Al2O3) inert fillers on TP347 steel sheets through the Czochralski method and high-temperature sintering. Results of the static contact angle test show that at 860°C, the contact angles of the molten ash on the coating surfaces of h-BN, ZrO2 and Al2O3 are 58°, 54° and 53°, respectively, which are greater than that (39°) of the steel sheet sample. The spreading radiuses of the three coatings are significantly less than that of the bare sample, indicating a strong anti-adhesion performance, in which the h-BN coating is the best. Spreading dynamic analysis of the bare and h-BN coating samples reveals that the spreading dynamics of both sample surfaces is driven by a combination of reaction, dissolution and diffusion. The inert filler in the coating makes the reaction and dissolution of molten ash on the coating surface weaker than those of the steel sheet. The micromorphology of the melt ash-sample sheet cross-section shows that the melt ash binds closely to the steel sheet sample oxide layer, whereas the boundary with the coating is clear and obvious. This result indicates that the coating can effectively weaken the wetting and permeability of the molten ash. The research results provide new ideas for precursor ceramic coating to solve the high-temperature melting ash adhesion problem of the heat exchanger surface.

Constructing three-dimensional network C, O Co-doped nitrogen-deficient carbon nitride regulated by acrylic fluoroboron overall marine antifouling

To deal with unwanted biofouling adsorption, which impacts the economy and the environment, significant research has been devoted to composite systems involving a photocatalyst combined with self-renewal resin to provide synergistic antifouling. Here, photocatalyst based on three-dimensional (3D) network of carbon–oxygen-doped nitrogen-deficient carbon nitride and acrylic fluoroboron polymer as a system was successfully synthesized. 3D networks carbon nitride with carbon–oxygen dopants and nitrogen defects were prepared as skeletons, which effectively support and regulate the hydrolysis rate of the polymer. These composite systems exhibits excellent diatom anti-adhesion performance and high antibacterial rates for Escherichia coli and Staphylococcus aureus of up to 91.87% and 88.52%, respectively. In addition, self-cleaning function of the composite system are proved by and higher efficiency of chemical oxygen demand (COD) removal owing to efficient charge-carrier separation and transfer within the 3D network carbon nitride network. The great potential applications of this strategy demonstrated in marine engineering in the future.

One-level microstructure-arrayed hydrophobic surface with low surface adhesion and strong anti-wetting function

To achieve both a low surface adhesion function and a high anti-wetting function, it is generally necessary to introduce multi-level micro–nano-structures on a surface. However, this will bring the difficulty of preparation technology, and the functions will fail due to the fact that the nanostructures can easily be damaged. In this research, the surface adhesion and anti-wetting properties of several typically one-level microstructure-arrayed hydrophobic surfaces are analyzed with the dynamics theory, including a square pillar-arrayed three-dimensional microstructure, a conical table-arrayed microstructure, and square frustum-arrayed microstructure. It is found that the anti-adhesion performance and anti-wetting property cannot achieve the best performance simultaneously on the one-level microstructure arrayed surfaces. Either the critical pressure of anti-wetting is finite when the surface adhesion is the lowest, or both the anti-adhesion and anti-wetting capacities are finite. However, an interesting phenomenon is found in that the square frustum-arrayed surface can not only achieve an almost infinite anti-wetting capacity when the distance between neighboring microstructures vanishes, but also reach near-zero adhesion when the square frustum reduces to a square pyramid. All the theoretical predictions are further verified by precise numerical simulations. The results of this paper should be helpful for the design of surfaces with low surface adhesion and strong anti-wetting functions in practical engineering.